Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$223.75	9.709%	$245.4739	$245.47	$245.45	$245.50
Purchase #2	$198.51	13.613%	$225.5332	$225.53	$225.55	$225.50
Purchase #3	$13.63	8.787%	$14.8277	$14.83	$14.85	$14.80
Purchase #4	$207.61	9.382%	$227.088	$227.09	$227.10	$227.10
Purchase #5	$220.81	11.331%	$245.83	$245.83	$245.85	$245.80
Purchase #6	$89.64	12.521%	$100.8638	$100.86	$100.85	$100.90
Purchase #7	$32.68	10.693%	$36.1745	$36.17	$36.15	$36.20
7 purchase totals =	$986.63		$1,095.7911	$1,095.78	$1,095.80	$1,095.80